When two 60 GHz-capable devices initially establish a connection with each other, they may perform a beamforming training procedure in order to identify optimal beamforming configurations for the directionally-beamformed links between them. Under some circumstances, an initial beamforming configuration for a given directionally-beamformed link, while providing acceptable link quality, may become suboptimal due to environmental changes that make superior link quality available via different beamforming settings. For example, if an object blocks a direct path between two 60 GHz devices at the time of initial beamforming training, but is subsequently removed, an initial beamforming configuration that uses reflective paths may become suboptimal. The availability of superior link quality in such a case may go undetected if beamforming training is only repeated in response to link quality degradation, because the link quality provided by the initial configuration may not have changed. In order to enable 60 GHz devices to discover link quality improvement opportunities under such circumstances, the beamforming training procedure may be repeated at periodic intervals without regard for current link quality.
However, under some circumstances, it may be possible for a given periodic repetition of the beamforming training procedure to result in the selection of beamforming parameters that actually degrade link quality. For example, changes in the direction of reflection off of an unstable reflector—such as the human body—during or soon after periodic beamforming training may result in sector selections that are inferior to those that were in effect prior to the periodic beamforming training. Link quality degradation in conjunction with periodic beamforming training may also result from various imperfections of the beamforming training protocol and its underlying assumptions with respect to antenna behavior.